I recently moved into a home that has a water run off from rains etc problem that was not evident when purchasing. We have graded the rear yard and put in catch basins and tiles to keep water from around the home. The garage floor always feels damp and if the humidity is high it is really slick. I intend to try to clean the floor to clean up mold from where the water has run through after a hard rain. The garage floor is stained black which I believe is mold buildup. I do not know how to find out if there is still a water pool under the slab that causes the slick floor. The interior of the house seems fine. House floor is several inches higher than the garage floor. Is there someone I can call to check this and/or correct this? Since we have taken care of the drainage problem will the water all eventually evaporate?
Only time will tell. You could bring in a consultant for a more informed opinion, but it will be still be just an opinion. If there is no other source of ground water and the run-off was adequately managed, it will eventually dry out. It's possible to drill a small, shallow monitor well to determine if there's a shallow water table problem. If there's any water at all, by monitoring over a period of time, it can be determined if it's accumulation slowly draining off or something more permanent that needs to be addressed.